Tire retreading or "recapping" is a common, widely-used procedure, particularly in the case of truck tires, to renew the tread of tires having a sound carcess but having their tread worn relatively thin as a result of many miles of use. In conventional retreading operations, a standard method involves abrading the road-engaging portion of the tire carcass to be retreaded, wrapping an un-cured rubber strip or "cushion" around it, adhesively applying a new tread rubber strip, which normally has been partially vulcanized, over the "cushion", and then, prior to introducing the assembly into a curing chamber where vulcanization of the tread rubber is completed and the tread rubber is vulcanized to the tire carcass, the tire carcass unit is placed upon a retreading "rim" which is annular in form, generally like the periphery of the wheel the tire is mounted on during normal use, but is conventionally made up of two axially-adjacent sections which interlock with each other upon rotation of one section relatively to the other. To effect this operation, a tube or "bladder" for the reception of air or other fluid is positioned in the tire carcass and then the tire carcass is positioned on one section of the rim, with the valve stem for introduction of the fluid extending through a slot formed in the rim section. Thereupon, the other section of the rim is placed in position and the two sections are interlocked by circumferentially rotating the second section relatively to the other. However, the slot is wider than the thickness of the valve/or inlet stem and, when the two sections of the rim are being interlocked and the two are rotated circumferentially relatively to one another, the tube has not yet been inflated and the valve stem may become twisted and/or severly bent relatively to the bladder and it may break off or tear away from the bladder or develop a leak at its juncture with the bladder. This is a problem which has not been satisfactorily solved in this art and continues to be a source of concern for the retreading field.
It is accordingly an object of the present invention to provide a construction for a tube or bladder used for tire retreading which prevents damage to the valve stem during assembly of the retreading apparatus.
It is another object of the invention to provide a retreading assembly wherein the tube or bladder used for retreading cooperates with its rim in such manner that its stem is prevented from damaging movements when the apparatus is assembled.